The present invention relates, generally, to sanitizing compounds and sanitization methods and, more particularly, to materials, methods and systems for sanitizing food processing equipment and facilities using ozone.
Microbial outgrowth is a primary cause of food spoilage. The presence of pathogenic microorganisms on food products can potentially lead to food-borne outbreaks of disease and can cause significant and economic loss to food processors. Food products can become contaminated within a food-processing environment. For example, processing equipment, such as knives, mixers and the like, can provide favorable locations for the growth of pathogenic microorganisms. Additionally, food contact surfaces, such as cutting boards and conveyor belts, and the like can become contaminated and support the growth of microorganisms. Also, microorganisms can be transported through a food processing facility by entrainment in the ambient air circulated throughout the food processing facility. Once airborne, microorganisms can become attached to numerous surfaces within the food processing facility, such as ceilings, air ducts, wall surfaces, floors and the like. The need to delay the onset of spoilage and to eliminate pathogens has led the food processing industry to seek effective means for disinfecting food processing equipment and facilities.
Presently, food processors use heat or chemicals to sanitize their food processing facility. Heat, in the form of steam or hot water, is a commonly used method for disinfecting food and for cleaning floors, walls and food contact surfaces. However, the efficiency of steam or hot water is low on large, exposed surface areas. Additionally, steam or hot water can adversely affect food products by thermally degrading the food products and by breaking down nutrients from the food products.
Widely used chemical sanitizers include chlorine-based chemicals and quaternary ammonium compounds. The chemical agents are relatively effective against microorganisms and reasonably inexpensive to apply. However, each particular chemical has a corresponding specific range of activity with respect to the population of pathogenic microorganisms commonly found in a food-processing environment. Additionally, the effectiveness of many chemicals depends upon carefully maintaining storage conditions and solution characteristics. For example, chlorine is effective at a pH of about 6 to about 8, and becomes less effective outside of that pH range. However, chlorine can produce toxic by-products that are harmful to human health, such as chloramines and trihalomethanes.
Another widely used chemical agent is ozone (O3). Ozone is a very strong oxidizing agent, having an oxidation potential more than 1.5 times that of chlorine, and approximately 1.2 times that of hydrogen peroxide. Ozone is normally produced by passing an oxygen-containing gas through ultraviolet light or a corona discharge. Ozone has been shown to be a highly reactive oxidant capable of destroying many cellular constituents in living cells. Further, an additional advantage of ozone relates to its natural decomposition into oxygen, an environmentally friendly gas. At low levels, ozone will decompose into oxygen within a few hours. Food processors have used gaseous ozone to disinfect foods stored in bulk storage containers, such as fruits and vegetables stored in warehouses. Additionally, processes have been developed using an ozone solution made by injecting ozone gas into water, which is then used to sanitize and disinfect food-processing surfaces.
Given that ozone decomposes into a non-toxic gas and that it will not impart odor or taint to food products, and leaves no residue after application, further development of ozone application technology is warranted. In particular, application technology is needed that maximizes the effectiveness of ozone""s inherent capability to kill pathogenic microorganisms.
The present invention is for an ozonated foam medium and production system, and for a method of sanitizing a food-processing environment-using ozonated foam. In one embodiment of the invention, an ozonated foam-sanitizing medium is prepared. The sanitizing medium is then applied to objects in the food-processing environment, or the ambient of the food-processing environment, or both, to the objects and the environment. The ozonated foam-sanitizing medium can be applied by a variety of means, such as spraying, atomization and liquid application.
In one embodiment of the invention, the ozonated medium is prepared by injecting a gas comprising ozone into an aqueous solution containing a foaming agent. Further, the ozone can be injected with a feed gas, such as oxygen, air and mixtures of oxygen and air. Additionally, the feed gas can be an inert gas or a mixture of air and an inert gas. Other feed gas combinations are possible, such as a mixture of an inert gas and oxygen O2, and a mixture of air and oxygen. The inert gas can be nitrogen (N2), carbon dioxide (CO2), argon (Ar), krypton (Kr), xenon (Xe), neon (Ne) and mixtures of these gases.
In another embodiment of the invention, an ozonated foam-sanitizing medium is prepared by injecting a gas comprising ozone into an aqueous solution containing a foaming agent, followed by injecting an inert gas directly into the sanitizing medium.
In yet another embodiment of the invention, an ozonated foam-sanitizing medium is prepared by mixing an aqueous ozone solution into an aqueous solution containing a foaming agent.
In a more particular embodiment of the invention, an ozonated foam-sanitizing medium is prepared with an initial ozone concentration, such that, after applying the ozonated foam-sanitizing medium, an ozone concentration of at least about 0.1% of the initial concentration is maintained up to about 30 minutes after applying the sanitizing medium. In accordance with the invention, the preparation of an ozonated foam functions to provide increased ozone concentration over extended periods of time following the application of the sanitizing foam. Thus, the ozone operates to kill pathogenic microorganisms over an extended period of time after its initial application.
In a still further embodiment of the invention, a foaming agent is mixed into an aqueous solution while maintaining the aqueous solution at a temperature of about 0xc2x0 C. to about 70xc2x0 C. A sanitizing medium is then formed by injecting a gas comprising ozone into the aqueous solution.
In a detailed aspect of the invention, ozonated foam is prepared by adding a surfactant to an aqueous solution and injecting ozone into the aqueous solution to form an initial ozone concentration of at least about 0.1 ppm. The ozonated foam is then sprayed on food contact surfaces of food processing equipment or facilities, and the ozonated foam is then allowed to stand on the food contact surfaces for a predetermined length of time. The ozonated foam is then washed away with an aqueous solution. By effectively confining ozone within a foam-sanitizing medium, the ozone can act on the food processing surfaces over a prolonged period of time. Also, by exposing pathogenic microorganisms to relatively high concentrations of ozone for a relatively long duration, the effectiveness at killing microorganisms can be increased. Additionally, the ozone can be recycled from the aqueous solution used to wash away the ozonated foam after it has completed a sanitization cycle.
A system for producing an ozonated foam medium includes an injector coupled to either a foam solution tank or to a foam separator. An ozone generator receives feed gas from a feed gas supply and produces a gas comprising ozone and transfers the gas comprising ozone to the injector. Both batch processing and continuous processing systems produce an ozonated foam medium for use in a food-processing facility.